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Data Tables in Microsoft Excel 2008

Data Tables let you see how the results of a formula change as its underlying variables change. After entering data, select the entire table and choose Data > Table. Then tell Excel which row input cell and column input cells you want the table to use. Finally, click OK. Excel will crunch the numbers and present a new Data Table.

Internet Backup via BackJack

With the growth of the Internet over the last few years, there's been added interest in backing up data over the Internet. It's been on my mind for a long time - as far back as 1992, I wrote an April Fools article in TidBITS-114 about a fictional company doing something along these lines.

Fast forward to 1998, and several companies have products that enable computer users to back up files over an Internet connection. They don't back up everything, only selected files, and files are encrypted for security reasons. Restoration happens over the Internet, or, if the amount of data is too large, via a CD-R sent to you overnight. Internet-based backup is perfect for a few important files, especially if you aren't comfortable with your offsite backup situation. On the downside, many people on TidBITS Talk said they were uncomfortable relying solely on encryption for security, and to my mind, an Internet backup strategy falls into the Minimal Backup camp, making it most useful as an off-site adjunct to a more comprehensive backup strategy.

One-Eyed Jacks -- The only Internet backup service currently available for Macintosh users is the just-released BackJack from Synectics, although I've heard rumblings about several other services that might appear soon. I've been playing with BackJack for a while now, and it has proved easy to set up and reliable so far.

BackJack's interface provides simple backup and recovery capabilities, which contributes to its ease-of-use, but the first version of the software lacks flexibility. It's clearly a first effort, albeit a functional one, and leaves room for future enhancement. For instance, to back up files, you select the folder that contains them, but there's no way to exclude specific files in that folder, and if you create a folder of aliases, BackJack doesn't resolve them and back up their originals. The company said it plans to address these issues soon in revisions to the free software.

BackJack does sport many basic backup features. You can create multiple sets of folders to back up, and each set can contain multiple folders. Each backup set can have a different automatic backup schedule, and BackJack has successfully kicked in every night and backed up my changed files. BackJack logs everything it does, plus it sends you an email report after each session. You can set how large the log grows, and other options enable you to determine how many revisions of a document are kept online and how long backed up files are kept online after being deleted locally. This functionality is tremendously important, since it enables you to revert to earlier versions of files and to recover if you delete a file without realizing.

The actual backup process is a bit slow, in part because of the transmission over the Internet (I have a 56K frame relay connection; those people with dialup Internet connections will obviously see somewhat slower transmission performance, plus they'll have to let BackJack dial out automatically). Speed isn't much of an issue though, since backups will usually take place unattended in the middle of the night. Another performance hit comes from the fact that BackJack compresses files using a built-in version of Aladdin's StuffIt technology and then encrypts them using a 128-bit key that you generate during setup. No one has broken the 128-bit encryption scheme BackJack uses, so security is high. However, be careful to store the extra copy of your encryption key off-site on a floppy; in case of a disaster that wipes out your computer, you won't be able to retrieve and decrypt your files without a copy of that key. The BackJack folks are investigating ways of avoiding that situation without compromising the security of the system.

Restoring a file from your backup over the Internet is easy - the Recover window provides a hierarchical view of your stored files, including any earlier revisions. The same interface enables you to enter dates for specific files to be deleted if you want to remove them from your backup. Although BackJack enables you to mark and unmark all the files, it lacks any way to retrieve just the latest versions of files or to find and mark specific ones through a search mechanism. If you back up a relatively small number of files that won't prove problematic, but it might with hundreds of files. The company has plans to offer a service that sends you all files on CD-R if necessary to avoid downloading all your data in the event of a complete recovery.

BackJack's documentation is available online and can be downloaded in HTML format. It's quite well done, although relatively basic, if mainly because the BackJack application doesn't have much depth. The documentation is good about answering the "Why" questions that always arise.

Ante Up -- Pricing is a little complicated, since BackJack charges based on the amount of data you back up, the time of day you send it, and how much storage space you use on the BackJack servers. There's a $17.50 one-time setup fee, a $3.50 monthly administration fee, plus data transfer and storage fees. BackJack's transfer fees are 14 cents per megabyte from 11 PM to 9 AM and 35 cents per megabyte from 9 AM to 11 PM. (Times are always your local time.) In addition, BackJack charges less than half a cent ($.0035) per megabyte per day for storage. Recovering data is always free, and you can use BackJack on multiple computers with same account for no additional charge.

You'll usually want to schedule BackJack to back up in the middle of the night, and you should be careful with what you choose to back up, avoiding applications and system files and, for instance, Web browser cache files if you plan to back up your Preferences folder.

In a sample situation where a user backs up 75 MB initially and then about 1 MB per day afterwards, the first month (including the setup fee) would cost about $45 and each subsequent month about $17. That pricing is in line with two popular PC Internet backup services: Atrieva charges $14.95 per month for up to two computers, and Connected Online Backup charges $19.95 per month per computer for up to 10 machines. Neither charges transfer or storage fees. They're probably betting that most people don't have the bandwidth to back up large quantities of data, plus they're counting on the fact most people won't back up Windows system files or applications because it's so difficult to restore them to a working state without doing a clean install.

In response to my comments about pricing, the BackJack folks noted that they felt uncomfortable using a flat rate pricing model that would in essence charge low-end users more to subsidize the high-end users who use far more of the system's capacity. That's a laudable goal, and I hope the pricing model doesn't dissuade people who are uncomfortable not knowing precisely how much they'd be paying.

These concerns aside, I'm quite impressed with BackJack as a first effort, and it's well worth a look for anyone interested in Internet backup, particularly those people planning on buying standalone iMacs immediately when they're released.

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